Conventional fluid production wells have been drilled and completed in subterranean formations often yield a desired fluid and other undesired components. For example, often in hydrocarbon wells the fluid produced will include a large percentage of undesired water production. Often included in the produced fluids is excess solids which is detrimental or incompatible with some pumping situations. For this type wells, as well as in other situations, progressive cavity pump (PCP) systems are the desired method of production.
Well economics is always driving factor in determining production systems and the viability of a particular well. The cost of operating a well is of particular concern for wells that are candidates for electrical progressive cavity pumps. A large portion of the production costs in these systems is the electrical costs and the cost of manufacturing and maintaining the PCP and electric motor. Typically electrical PCPs are driven by two-pole motors utilizing an 8:1 gearbox. Recently, four-pole motors with a 4:1 gearbox have been utilized by Schlumberger to drive PCPs providing improved system reliability relative to the two-pole motors. However, it has been realized that additional system reliability and efficiency is available. Further, the increased reliability of the four-pole motors does not utilize the ready supply of the two-pole, three-phase induction motors available.
Therefore, it is a desire to provide an electrical progressive cavity pump that addresses drawbacks of the prior art electrical progressive cavity pump systems. It is an additional desire to provide an electrical progressive cavity pump that facilitates tapping into the available supply of electrical motors. It is a still further desire to provide an electrical motor that more readily operates within its ideal frequency range to drive PCPs than the prior electrical drive motors.